The invention relates to a gear pump with auxiliary gearing, in which the liquid-conveying pumping gears do not permit synchronous movement transmission and the auxiliary gearing ensures positive drive of the liquid-conveying pumping gears. In these gear pumps the rotational adjustment of the gears of the auxiliary gearing in relation to the liquid-conveying pumping gears must be very accurately made in order to enable the desired functioning of the latter to be fully ensured and to prevent incorrect contact between the tooth flanks of the two gears, that is to say, to permit a predetermined flank clearance (as described for example in U.S. Pat. No. 3,640,650).
Hitherto this rotational adjustment could be made only at considerable expense.
One possible way lies in providing the auxiliary gearing with helical teeth and making one gear adjustable for axial movement in a keyway. By means of the axial displacement the rotary adjustment of the two auxiliary gears in relation to one another can be controlled.
In another procedure the keyway of one auxiliary gear is produced subsequently, or with the aid of special manufacturing devices, in accordance with the correct engagement of the two liquid-conveying pumping gears, in which case the keyway must be correctly positioned with great accuracy.